Accurate nonlinear modeling and verification of MMIC amplifier

An accurate MESFET nonlinear model and a reliable model verification approach that uses the on-wafer RF probing method are presented. The nonlinear model is based on small-signal S-parameter characterization of the MESFET at a wide range of bias voltages and is capable of accurately predicting the MMIC amplifier performances at various bias voltages, frequencies, and input power levels (both small and large signals). A model verification scheme is used that was designed to eliminate many measurement uncertainties. In this approach, the nonlinear model is verified by comparing the simulation results of a single-stage MMIC amplifier with the measurement data. The S-parameters of the amplifier's input and output matching circuits are first accurately measured using the on-wafer RF probes. These data are then input to the simulation program for the complete amplifier simulation. Simulation results for a MMIC amplifier at various frequencies, bias voltages, and power levels agree well with the measurement data.>